Annular heat-treating furnace



June 1, 1954 w HOLcROFT 2,680,011

ANNULAR HEAT TREATING FURNACE Filed Nov. 17, 1952 2 Sheets-Sheet 1 INVENTOR.

WALTER H HOLCROFT BY m WmM ATTORNEY S June 1, 1954 w. H. HOLCROFT ANNULAR HEAT TREATING FURNACE 2 Sheets-Sheet 2 Filed Nov. 17, 1952 FIG.2.

b\ b\Q INVENTOR.

WALTER H. H OLGRO FT ATTORNEYS Patented June I, 1954 2,680,011 ANNULAR HEAT-TREATING FURNACE Walter H. Holcroft, Detroit, Mich, assignor to Holcroft & Company, Detroit, Mich, a corporation of Michigan Application November 17, 1952, Serial No. 320,938

2 Claims.

The invention relates to heat treating furnaces which are of annular form and in which the work is carried through nearly a complete cycle from its point of introduction into the furnace chamber to the point of withdrawal therefrom. Where a furnace of this type is used for heating steel for forging the temperature within the furnace chamber must be from 2200 F. to 2400 F. This temperature is too high for any metallic work conveyor within the chamber and therefore other means must be provided for advancing the work through its cycle. It is the object of the invention to obtain a construction adapted for such purpose. and to this end the invention consists in the construction as hereinafter set forth.

In the drawings:

Figure 1 is a plan view partly in horizontal section through the furnace;

Figure 2 is a vertical cross-section through a portion of the furnace on line 2-2, Figure 1.

With certain constructions of annular furnaces of this general type the work has been carried through its cycle within the furnace chamber by providing a rotary hearth on which it is deposited at a loading point and from which it is withdrawn after completing or nearly completing a cycle. There are certain difiiculties that are encountered with such constructions, one of which is that the super-structure of the furnace must be supported independently of the hearth and by an external metallic framework, including columns extending to the base on which the rotary hearth is supported. These columns may interfere with work introduced into the furnace chamber, particularly if the latter has an unheated portion which projects outward beyond the furnace wall. I have therefore devised a construction in which the hearth portion of the furnace is stationary and the super-portion is revoluble and carries the work therewith. As illustrated A is the stationary hearth member of the furnace which is provided with upwardly extending concentric inner and outer walls A and A Adjacent to these walls respectively within the annulus and outside thereof is a metallic framework including inner and outer post members B and B arranged at spaced intervals. Members of angle cross-section B and B mounted on said post members respectively inside and outside of the walls A and A and extending completely around the circle form in connection with the walls an annular sealing channel. Also mounted at the upper ends of certain of the columns B and B are roller supports C. D is the super-structure of the furnace which is of corresponding annular form having an arched top D' and depending side walls D and D There is also an external reinforcing and supporting frame which includes vertical members D and D cross members D above the arched top, and annular members D secured to the lower ends of the members D and D and forming shelves for supporting the walls D and D Also connected to the lower ends of the members D and D is an annular track member E which rests upon the roller C being retained by roller flanges C.

The outer wall D of the member D is provided with a series of apertures therein through which work may be inserted to extend within the furnace chamber. Frequently this work requires heating of only the inner end portion thereof, the outer portion remaining outside of the furnace wall but carried thereby. Due to the fact that the rotary member D is supported by the track member E and roller 0 this will be completely out of the path of the outwardly projecting portions of the work so as not to interfere therewith. Each of the members D is provided with a downwardly extending flange D which enters the channel B or B Thus, if these channels are filled with fluid or with granular material an air seal will be formed between the hearth member A and the super-structure D.

For heating the furnace, burners for either gaseous fuel or oil are inserted through apertures A in the outer wall of the hearth member A to direct the flame laterally within the portion of the chamber enclosed by this member. Preferably refractory material A is placed adjacent to the inner wall of the member A so as to form a curved surface for directin the flame upward into the chamber portion which is within the member D.

The member D is rotated preferably with a step by step movement by any suitable mechanism. As shown, this mechanism comprises a cylinder E. mounted on a bracket E extending upwardly from the frame of the stationary hearth member, and the piston E of this cylinder carries a pawl E for engaging shoulders or ratchet teeth on an annular member F secured to the frame of the rotary member.

What I claim as my invention is:

l. A heat treating furnace comprising a stationary annular hearth member and a rotary annular super-member, both formed of a refractory material and having inner and outer annular side wall portions in substantial alignment in the two members and which in conjunction enclose an annular furnace chamber, a metallic suspension frame for the super-member includin portions adjacent to said inner and outer annular side wall portions thereof, a metallic frame for said hearth member also having portions adjacent to the inner and outer annular side walls thereof, a roller support for the side portion of the super-member frame on the side portion of the hearth frame including an annular track on the one and spaced rollers on the other, and means on said super-member for admitting work into said chamber and for carrying it therein around the circuit.

2. The construction as in claim 1 in which said super-member is provided with a series of openings in its outer wall through which in- 4 ner end portions of work may be inserted into the furnace chamber while the outer end portions thereof project radially outward, the space surrounding said wall being free from any obstruction interfering with the travel of said projecting portions through the circuit.

References Cited in the file of this patent UNITED STATES PATENTS 10 Number Name Date 222,335 Webb Dec. 2, 1879 452,00? Sternbergh May 12, 1891 2,486,506 Sylvester Nov. 1, 1949 2,502,827 Cooper Apr. 4, 1950 15 2,622,861 Talley Dec. 23, 1952 

